1. Field of the Invention
The present invention relates to a substrate processing apparatus and a method of manufacturing a semiconductor device.
2. Description of the Related Art
In recent years, semiconductor devices such as flash memories have become highly integrated. Thus, a pattern size is being markedly downscaled. When patterns are formed, a predetermined processing process, such as an oxidation process, a nitridation process, etc., may be performed on a substrate as one process of a manufacturing process.
As a method of forming the patterns, a groove is formed between circuits, and a seed film, a liner film, or a line is formed. With recent miniaturization, the groove is formed to obtain a high aspect ratio.
To form the liner film, it is necessary to form a film having good step coverage, which has no variation in film thickness even in an upper side surface, a middle side surface, a lower side surface, and a lower portion of the groove. Due to the film having the good step coverage, a semiconductor device may have uniform characteristics between grooves, and a variation in the characteristics of the semiconductor device may be inhibited.
A process of processing the groove having a high aspect ratio by heating a gas or using a plasma-state gas has been attempted. However, it was difficult to form a film having good step coverage.
As a method of forming the film, there is an alternate supply method of alternately supplying at least two process gases to cause a reaction on the surface of a substrate.
Meanwhile, since it is necessary to uniformize the characteristics of the semiconductor device, gases need to be uniformly supplied to a surface of the substrate during formation of a thin film. Thus, a single-wafer-type apparatus capable of uniformly supplying gases to a processed surface of the substrate has been developed. In the single-wafer-type apparatus, for example, a shower head including a buffer space is installed on a substrate to supply gases more uniformly.
In the alternate supply method, a process of purging a remnant gas using a purge gas during the supply of each gas is known to inhibit a reaction of respective gases on the surface of the substrate. However, a film forming time is retarded due to addition of the purge process. Accordingly, to reduce a process time, the remnant gas is exhausted by supplying a large amount of purge gas.
In addition, a type of shower head in which a path or buffer space for each gas is installed to prevent mixture of respective gases may be considered. However, since such a structure is complicated, maintenance becomes burdensome, and costs increase. For this reason, it is practical to use the shower head in which supply systems of two gases and a purge gas are provided in a single buffer space.
When the shower head including the buffer space common to two kinds of gases is used, it may be inferred that remnant gases react with each other in the shower head and adhered materials are deposited on an inner wall of the shower head. To prevent the deposition of the adhered materials, an exhaust port is preferably installed in a buffer chamber to efficiently remove the remnant gases from the buffer chamber, and an atmosphere of the buffer chamber is preferably exhausted through the exhaust port. In this case, a component for preventing two gases and the purge gas (which are to be supplied to a process chamber) from diffusing toward the exhaust port for exhausting the buffer space, for example, a gas guide for forming the flow of gases, is installed in the buffer chamber. For example, the gas guide is installed between the exhaust port for exhausting the buffer space and a supply hole for supplying the two gases and the purge gas. The gas guide is preferably installed in a radial shape toward a dispersion plate of the shower head. To efficiently exhaust gases from an inner space of the gas guide, an inner side of the gas guide is in communication with a space between the exhaust port for exhausting the buffer space and the gas guide. Specifically, an outer circumferential end of the gas guide is in communication with a space between the exhaust port for exhausting the buffer space and the gas guide.